1. Field of the Invention
This invention relates to conduit prover apparatus and, more particularly, to air motivated or driven apparatus for proving the integrity of a conduit.
2. Description of the Prior Art
After a conduit has been laid, the integrity of the conduit must be proved before the trench, or the like, in which the conduit is disposed, may be backfilled. The integrity of the conduit is generally proven by moving or forcing a "fish line" through the conduit. The "fish line" is generally a length of relatively small and lightweight string, nylon filament, etc. The lightweight line is able to pass obstructions which may be in the pipe or conduit, such as rocks, dirt, or other debris which may result from the installation or laying of the conduit. The fish line is relatively light in weight and is extremely flexible so that breaks in the conduit, if any, will not affect it.
After the initial fish line is passed through the conduit, the line is then used to pull heavier line through the conduit or pipe, and the heavier, stronger line is in turn used to pull through yet heavier line, if necessary. Eventually, line of desired size and strength extends fully through the conduit. An appropriate mandrel is then secured to the heavy, strong line. The mandrel is then pulled through the conduit to prove the integrity of the conduit.
The mandrel is typically a relatively flexible disc or the like which is mechanically pulled through the conduit. Typically, several different mandrels are passed through the conduit, with the mandrels increasing in size from small to the large. The smallest mandrel is pulled through the conduit, and, if it moves through easily, a mandrel of slightly larger diameter is pulled through. This procedure continues until a mandrel of a diameter slightly less than the diameter of the conduit is pulled through. The different sized mandrels allow objects of different sizes to be cleaned from the pipe so that not only the physical integrity of the pipe is proven, but also the cleanliness aspect of the integrity of the pipe is also assured. If there are any breaks in the pipe, such breaks will be detected by the inability of the mandrel to pass through the pipe. The specific location of such break, or large obstruction, may be easily determined by measuring the distance that the mandrel has moved.
Using the apparatus of the prior art, it is obvious that proving the integrity of a conduit is a relatively time-consuming process, requiring substantial manpower for relatively long periods of time. With the apparatus of the present invention, the structural integrity of a conduit is proved at the same time that the conduit is cleaned of all debris. Since several operations are accomplished at one time, a substantial savings in labor and effort is effected. At the same time, the mandrel is able to be secured to a relatively large cable or line so that the pulling line or cable moves through the conduit at the same time that the conduit's integrity is proven. Again, there is a savings in time, and the time savings translates into a savings of manpower and equipment.